A further 44% are overweight, while problem drinking and reliance on multiple medications is also on the rise among older people.

Despite the obvious health risks, the over-50s generally report high levels of satisfaction with quality of life and their incomes have remained stable.

The findings are revealed in the latest report by the Irish Longitudinal Study on Ageing (Tilda), a national survey of more than 8,000 people aged 50 and over.

Participants were interviewed between April 2012 and January 2013, during, as researchers note, a period of considerable social and economic change in Ireland.

Health Minister James Reilly said the latest report flags up serious concerns about the health of the over-50s.

"I am encouraged by some of the findings in this report, particularly those that show that, in general, the over-50s enjoy a good quality of life and report their health as excellent or very good," he said.

"However, I am also struck by some worrying trends, particularly the levels of non-communicable diseases and their co-morbidities.

"The finding that 35% of the over-50s are obese with a further 44% overweight is another serious cause for concern."

Obesity is strongly associated with heart disease and diabetes.

The report also found:

:: About one third of the over-50s report low levels of physical activity, with more women than men reporting low exercise;

:: More than half of those aged 75 and over have arthritis;

:: Smoking among over-50s is down from just over 18% to 16.5% since participants were last interviewed in 2009 and 2010;

:: Problem drinking has risen for both men and women - from 17% to 22% in men and from 8% to 11% in women;

:: Those taking five or more medications has increased from 21% to 26%.

Professor Rose Anne Kenny, who heads up the Tilda research project, said the findings gave cause for concern, particularly as Ireland's population is ageing.

"Given current and future dramatic changes in the Irish population, with one fifth of people aged over 65 by 2060, Tilda will greatly assist new policy initiatives to address health behaviours and disease prevention so that our later life years can be healthy and independent," she said.

Launched in November 2006, Tilda is tracking the health, social and economic circumstances of 8,000 people over the age of 50 over a 10-year period.

The study - based on similar projects in the UK and the US - is being spearheaded by Trinity College Dublin with the help of researchers from the Economic and Social Research Institute, National University of Ireland Galway, Royal College of Surgeons in Ireland, University College Cork and Waterford Institute of Technology.

It is funded by the Department of Health, Irish Life and the Atlantic Philanthropies.